Electric device with torque vectoring function

ABSTRACT

Disclosed is an electric differential with a torque vectoring function. The electric differential includes: a main drive mechanism; a bevel gear differential; a TV control drive mechanism used for outputting control power; a first single-row planetary gear train, of which a first sun gear is coaxially and fixedly connected with a first half shaft and a first gear ring is connected with a control output end; a second single-row planetary gear train, of which a second gear ring is fixed to a drive axle housing, a second planet carrier is fixedly connected with a first planet carrier and a second sun gear is supported on the first half shaft through a bearing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No.201710266606.3 with a filing date of Apr. 21, 2017. The content of theaforementioned applications, including any intervening amendmentsthereto, are incorporated herein by reference.

TECHNICAL FIELD

The present invention belongs to the technical field of transmission ofelectric vehicles, and particularly relates to an electric differentialwith a torque vectoring function.

BACKGROUND OF THE PRESENT INVENTION

Due to the energy crisis and the increasing attention to environmentalprotection, a new energy automobile is the development direction offuture automobiles. An electric automobile has been rapidly developedworldwide. Compared with a traditional internal combustion engineautomobile, the electric automobile has better economy and environmentfriendliness, and has significant advantages in the environmentalprotection aspect due to the characteristic of almost zero emission.Meanwhile, due to the characteristics of a drive motor, such as rapidresponse, low speed, large torque and the like, the electric automobilehas better acceleration performance; the rotation speed and the torqueof the motor are easy to acquire; and the electric automobile may becontrolled more accurately. Therefore, the electric automobile has greatdevelopment potential.

The electric automobile is generally driven to run by adopting a powerassembly composed of a motor and a drive axle or a power assemblycomposed of the motor, a transmission and the drive axle. Due to thedefects of large unsprung mass, poor heat dissipation of a hub motor andthe like, an electric automobile driven by the hub motor is not producedin large scale. Therefore, most of the power assemblies of existingelectric automobiles include the drive axle.

A differential is an important component in the drive axle. Because of a“differential without differential torque” principle in thedifferential, a drive torque of the automobile may be only equallyvectored to both sides of left and right wheels. In this way, groundadhesive force cannot be well utilized under the condition that groundadhesion is not uniform; and even slippage of the wheels and otherunsteady running conditions may be easily caused on one side with lowadhesion, so that the adhesive capability of drive wheels cannot beachieved. Meanwhile, when the automobile makes a turn at high speed, aload may be transferred from an inside wheel to an outside wheel. Evenif the ground adhesion is good, the adhesive capability of the outsidewheel may be higher than that of the inside wheel. At this moment, thetorque is equally vectored to the inside and outside wheels by thetraditional differential, which may cause that the inside wheel reachesan adhesion limit and slips, and the automobile is instable. If part ofthe torque of the inside wheel is transferred to the outside wheel,lateral force margin of the inside wheel may be increased to prevent thewheels from slipping, and an additional yawing moment may be generatedfor the complete vehicle. The yawing moment may help to promote andguide the vehicle to turn, thereby increasing turning maneuverabilityand ultimate turning capability of the vehicle. At present, thetechnology is applied to some high-end sports cars and high-grade SUVsin a form of a torque vectoring differential, such as a super handlingall-wheel drive system (SH-AWD) developed by Honda Company, a superactive yawing control (SAYC) system developed by Mitsubishi Corporation,and the like. However, the technology is not widely applied in theelectric automobile.

SUMMARY OF PRESENT INVENTION

A purpose of the present invention is to provide an electricdifferential with a torque vectoring function, for overcoming the defectthat left and right output torques of a differential are equal andcannot be regulated.

A technical solution provided by the present invention is as follows:

An electric differential with a torque vectoring function includes:

a main drive mechanism arranged on one side of a differential, whereinan output end of the main drive mechanism is connected with adifferential housing for transferring rotating power to the differentialhousing to drive a vehicle to run;

a TV control drive mechanism arranged on the other side of thedifferential for outputting torque vectoring control power;

a first single-row planetary gear train including a first sun gear, afirst planetary gear, a first planet carrier and a first gear ring,wherein the first sun gear is coaxially and fixedly connected with afirst half shaft, and the first gear ring is connected with an outputend of the TV control drive mechanism;

a second single-row planetary gear train including a second sun gear, asecond planetary gear, a second planet carrier and a second gear ring,wherein the second gear ring is fixed to a drive axle housing, thesecond planet carrier is fixedly connected with the first planetcarrier, and the second sun gear is rotatably supported on the firsthalf shaft; and

a third single-row planetary gear train including a third sun gear, athird planetary gear, a third planet carrier and a third gear ring,wherein the third sun gear is coaxially and fixedly connected with thefirst half shaft, the third gear ring is fixedly connected with thesecond sun gear, and the third planet carrier is fixedly connected withthe differential housing, wherein

the second single-row planetary gear train and the first single-rowplanetary gear train have the same characteristic parameter.

Preferably, the TV control drive mechanism includes a TV control motorand a TV reducing mechanism.

Preferably, the TV reducing mechanism includes:

a fourth single-row planetary gear train including a fourth sun gear, afourth planetary gear, a fourth planet carrier and a fourth gear ring,wherein the fourth sun gear is fixedly connected with the hollow outputshaft, and the fourth gear ring is fixed to the drive axle housing; and

a fifth single-row planetary gear train including a fifth sun gear, afifth planetary gear, a fifth planet carrier and a fifth gear ring,wherein the fifth sun gear is fixedly connected with the fourth planetcarrier, the fifth gear ring is fixed to the drive axle housing, and thefifth planet carrier as a control output end is connected with the firstgear ring.

Preferably, the main drive mechanism includes a main drive motor and amain reducing mechanism.

Preferably, the TV control motor includes a hollow output shaft; and thefirst half shaft is rotatably supported on the hollow output shaft andpenetrates out of the hollow output shaft

Preferably, the main reducing mechanism includes:

a seventh single-row planetary gear train including a seventh sun gear,a seventh planetary gear, a seventh planet carrier and a seventh gearring, wherein the seventh sun gear is fixedly connected with an outputshaft of the main drive motor, and the seventh gear ring is fixed to thedrive axle housing; and

a sixth single-row planetary gear train including a sixth sun gear, asixth planetary gear, a sixth planet carrier and a sixth gear ring,wherein the sixth sun gear is fixedly connected with the seventh planetcarrier, the sixth gear ring is fixed to the drive axle housing, and thesixth planet carrier is fixedly connected with the differential housing.

Preferably, the main drive motor includes a hollow output shaft; and asecond half shaft is rotatably supported on the hollow output shaft andpenetrates out of the hollow output shaft.

An electric differential with a torque vectoring function includes:

a main drive mechanism arranged on one side of a differential, whereinan output end of the main drive mechanism is connected with adifferential housing for transferring rotating power to the differentialhousing to drive a vehicle to run;

a TV control drive mechanism arranged on the other side of thedifferential for outputting torque vectoring control power;

a first single-row two-stage planetary gear train including a first sungear, a first two-stage planetary gear, a first planet carrier and afirst gear ring, wherein the first sun gear is coaxially and fixedlyconnected with a first half shaft, and the first gear ring is connectedwith an output end of the TV control drive mechanism;

a second single-row two-stage planetary gear train including a secondsun gear, a second two-stage planetary gear, a second planet carrier anda second gear ring, wherein the second gear ring is fixed to a driveaxle housing, the second planet carrier is fixedly connected with thefirst planet carrier, and the second sun gear is rotatably supported onthe first half shaft; and

a third single-row planetary gear train including a third sun gear, athird planetary gear, a third planet carrier and a third gear ring,wherein the third sun gear is coaxially and fixedly connected with thefirst half shaft, the third gear ring is fixedly connected with thesecond sun gear, and the third planet carrier is fixedly connected withthe differential housing, wherein

the second single-row two-stage planetary gear train and the firstsingle-row two-stage planetary gear train have the same characteristicparameter.

An electric differential with a torque vectoring function includes:

a main drive mechanism arranged on one side of a differential, whereinan output end of the main drive mechanism is connected with adifferential housing for transferring rotating power to the differentialhousing to drive a vehicle to run;

a TV control drive mechanism arranged on the other side of thedifferential for outputting torque vectoring control power;

a first single-row planetary gear train including a first sun gear, afirst planetary gear, a first planet carrier and a first gear ring,wherein the first sun gear is coaxially and fixedly connected with afirst half shaft, and the first gear ring is connected with an outputend of the TV control drive mechanism;

a second single-row planetary gear train including a second sun gear, asecond planetary gear, a second planet carrier and a second gear ring,wherein the second gear ring is fixed to a drive axle housing, thesecond planet carrier is fixedly connected with the first planetcarrier, and the second sun gear is rotatably supported on the firsthalf shaft; and

a third single-row two-stage planetary gear train including a third sungear, a third two-stage planetary gear, a third planet carrier and athird gear ring, wherein the third sun gear is coaxially and fixedlyconnected with the first half shaft, the third gear ring is fixedlyconnected with the second sun gear, and the third planet carrier isfixedly connected with the differential housing, wherein

the second single-row planetary gear train and the first single-rowplanetary gear train have the same characteristic parameter.

An electric differential with a torque vectoring function includes:

a main drive mechanism arranged on one side of a differential, whereinan output end of the main drive mechanism is connected with adifferential housing for transferring rotating power to the differentialhousing to drive a vehicle to run;

a TV control drive mechanism arranged on the other side of thedifferential for outputting torque vectoring control power;

a first single-row two-stage planetary gear train including a first sungear, a first two-stage planetary gear, a first planet carrier and afirst gear ring, wherein the first sun gear is coaxially and fixedlyconnected with a first half shaft, and the first gear ring is connectedwith an output end of the TV control drive mechanism;

a second single-row two-stage planetary gear train including a secondsun gear, a second two-stage planetary gear, a second planet carrier anda second gear ring, wherein the second gear ring is fixed to a driveaxle housing, the second planet carrier is fixedly connected with thefirst planet carrier, and the second sun gear is rotatably supported onthe first half shaft; and

a third single-row two-stage planetary gear train including a third sungear, a third two-stage planetary gear, a third planet carrier and athird gear ring, wherein the third sun gear is coaxially and fixedlyconnected with the first half shaft, the third gear ring is fixedlyconnected with the second sun gear, and the third planet carrier isfixedly connected with the differential housing, wherein

the second single-row two-stage planetary gear train and the firstsingle-row two-stage planetary gear train have the same characteristicparameter.

The present invention has beneficial effects as follows:

1, the electric differential with the torque vectoring function providedin the present invention overcomes the defect of “differential withoutdifferential torque” in the differential in the traditional drive axleand may vector drive torques of the automobile to wheels on the left andright sides according to the control need of control logic. On premiseof not changing the total longitudinal drive torque, the function ofunequal vectoring of the torques to the wheels on the left and rightsides is realized, thereby increasing the turning maneuverability anddriving pleasure of the vehicle;

2, according to the electric differential with the torque vectoringfunction provided in the present invention, the TV control motor and themain drive motor are coaxially arranged, so that the structure is morecompact and an arrangement space is reduced; and

3, according to the electric differential with the torque vectoringfunction provided in the present invention, the mass belongs to thesprung mass. Therefore, unlike a hub motor, the unsprung mass will notbe obviously increased, so a smoothness influence is small duringrunning of the automobile.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural schematic diagram of an electric differentialwith a torque vectoring function in embodiment 1 of the presentinvention;

FIG. 2 is a structural schematic diagram of an electric differentialwith a torque vectoring function in embodiment 2 of the presentinvention;

FIG. 3 is a structural schematic diagram of an electric differentialwith a torque vectoring function in embodiment 3 of the presentinvention;

FIG. 4 is a structural schematic diagram of an electric differentialwith a torque vectoring function in embodiment 4 of the presentinvention;

FIG. 5 is a schematic diagram of a torque flow direction of an electricdifferential with a torque vectoring function when an automobile goesstraight in the present invention;

FIG. 6 is a schematic diagram of a torque flow direction of an electricdifferential with a torque vectoring function when an automobilenormally turns in the present invention;

FIG. 7 is a schematic diagram of a torque flow direction of an electricdifferential with a torque vectoring function during left turning of anautomobile and an operation of a torque vectoring device in the presentinvention; and

FIG. 8 is a schematic diagram of a torque flow direction of an electricdifferential with a torque vectoring function during right turning of anautomobile and an operation of a torque vectoring device in the presentinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention is further described below in detail incombination with drawings to enable those skilled in the art toimplement the present invention with reference to words in thedescription.

Embodiment 1

As shown in FIG. 1, the present invention provides an electricdifferential with a torque vectoring function, and is mainly composed ofa torque vectoring device 2000, a traditional bevel gear differential1400, a main drive motor reducing mechanism 1500 and a main drive motor1002.

In the present embodiment, the torque vectoring device 2000 ispositioned on a left side of the drive axle (and can also be arranged ona right side of the drive axle by changing position with the main drivemotor 1002) and mainly composed of a TV control motor 1001, a TVreducing mechanism 1100, a two-row planetary TV coupling mechanism 1200and a single-row planetary differential coupling mechanism 1300.

The TV control motor 1001 is a hollow shaft type inner rotor motor andis connected with a first half shaft 1402 of a wheel on the left side topenetrate out of a hollow rotor shaft inner hole; a hollow shaft typeinner rotor is connected with a sun gear 1014 of a fourth planetary geartrain 1010 by a spline; and an output torque of the TV control motor1001 is inputted to the fourth planetary gear train 1010. The TV controlmotor 1001 is supported on the first half shaft 1402 by a bearing, and astator and a housing of the TV control motor 1001 are fixed with a driveaxle housing.

The TV reducing mechanism 1100 mainly includes the fourth planetary geartrain 1010 and a fifth planetary gear train 1020. The fourth planetarygear train 1010 includes the sun gear 1014, three planetary gears 1012distributed along a circumference uniformly, a planet carrier 1013 andan inner gear ring 1011 fixed to the drive axle housing. The sun gear1014 is connected with the hollow shaft type inner rotor of the TVcontrol motor 1001 by a spline, and the planet carrier 1013 and a sungear 1024 of the fifth planetary gear train 1020 are formed into awhole. The fifth planetary gear train 1020 includes a sun gear 1024,three planetary gears 1022 distributed along a circumference uniformly,a planet carrier 1023 and an inner gear ring 1021 fixed to the driveaxle housing. The sun gear 1024 is supported on the first half shaft1402 by a bearing, and the planet carrier 1023 and an inner gear ring1031 of a first planetary gear train 1030 are formed into a whole.

Preferably, the TV reducing mechanism 1100 may be composed of asingle-row planetary gear train, a multi-row planetary gear train orreducing mechanisms of other forms. Therefore, transformation of theform of the reducing mechanism 1100 is not regarded as the innovation ofthe present invention.

The two-row planetary TV coupling mechanism 1200 mainly includes thefirst planetary gear train 1030 and a second planetary gear train 1040.The first planetary gear train 1030 and the second planetary gear train1040 must have the same planetary row characteristic parameters andconsistent types of the planetary rows. The first planetary gear train1030 includes a sun gear 1034, three planetary gears 1032 distributedalong a circumference uniformly, the planet carrier 1033 and the innergear ring 1031, wherein the inner gear ring 1031 and the planet carrier1023 of the fifth planetary gear train 1020 are formed into a whole, thesun gear 1034 and the first half shaft 1402 are connected by a spline,and the planet carrier 1033 and the planet carrier 1043 of the secondplanetary gear train 1040 are formed into a whole. The second planetarygear train 1040 includes the sun gear 1044, three planetary gears 1042distributed along a circumference uniformly, a planet carrier 1043 andan inner gear ring 1041 fixed to the drive axle housing, wherein the sungear 1044 and the inner gear ring 1051 of the third planetary gear train1050 are formed into a whole, and the sun gear 1044 is supported on thefirst half shaft 1402 by the bearing.

The single-row planetary differential coupling mechanism 1300 is mainlycomposed of the third planetary gear train 1050. The third planetarygear train 1050 includes a sun gear 1054, three planetary gears 1052distributed along a circumference uniformly, a planet carrier 1053 andthe inner gear ring 1051, wherein the sun gear 1054 and the first halfshaft 1402 are connected by a spline, the inner gear ring 1051 and thesun gear 1044 of the second planetary gear train 1040 are formed into awhole, and the planet carrier 1053 is fixed to a differential housing1401.

The traditional bevel gear differential 1400 is mainly composed of thedifferential housing 1401, the first half shaft 1402, a second halfshaft 1403, a first half shaft gear 1404, a second half shaft gear 1405,two planetary bevel gears 1406 and 1407, and a planetary gear shaft1408, wherein the first half shaft gear 1404 is connected with the firsthalf shaft 1402 by a spline, the second half shaft gear 1405 isconnected with the second half shaft 1403 by a spline, and thedifferential housing 1401 is supported on the second half shaft 1403 bya bearing.

The main drive motor reducing mechanism 1500 is positioned on the rightside of the drive axle and mainly composed of a sixth planetary geartrain 1060 and a seventh planetary gear train 1070. The sixth planetarygear train 1060 includes a sun gear 1064, three planetary gears 1062distributed along a circumference uniformly, a planet carrier 1063 andan inner gear ring 1061 fixed to the drive axle housing, wherein theplanet carrier 1063 and the differential housing 1401 are formed into awhole, the sun gear 1064 and a planet carrier 1073 of the seventhplanetary gear train 1070 are formed into a whole, and the sun gear 1064is supported on the second half shaft 1403 by a bearing. The seventhplanetary gear train 1070 includes a sun gear 1074, three planetarygears 1072 distributed along a circumference uniformly, a planet carrier1073 and an inner gear ring 1071 fixed to the drive axle housing,wherein the sun gear 1074 is connected with the hollow inner rotor shaftof the main drive motor 1002 by a spline.

Preferably, the main drive motor reducing mechanism 1500 may be composedof a single-row planetary gear train, a multi-row planetary gear trainor reducing mechanisms of other forms. Therefore, transformation of theform of the main drive motor reducing mechanism 1500 is not regarded asthe innovation of the present invention.

The main drive motor 1002 is positioned on the right side of the driveaxle, is a hollow shaft type inner rotor motor and is connected with thesecond half shaft 1403 of a wheel on the right side to penetrate out ofa hollow rotor shaft inner hole. A hollow shaft type inner rotor isconnected with the sun gear 1074 of a seventh planetary gear train 1070by a spline. A drive torque may be inputted into the main drive motorreducing mechanism 1500 by the main drive motor 1002 through the sungear 1074, acts on the differential housing 1401 and is finally equallyvectored to the first half shaft 1402 and the second half shaft 1403.The main drive motor 1002 is supported on the second half shaft 1403 bythe bearing, and a stator and a housing of the main drive motor 1002 arefixed with the drive axle housing.

Embodiment 2

As shown in FIG. 2, in the present embodiment, the first planetary geartrain 1030 and the second planetary gear train 1040 in the two-rowplanetary TV coupling mechanism 1200 are single-row planetary geartrains, and the third planetary gear train 1050 in the single-rowplanetary differential coupling mechanism 1300 is a two-stage planetarygear train. The structural simplified diagram is shown in the figure.

Embodiment 3

As shown in FIG. 3, in the present embodiment, the first planetary geartrain 1030 and the second planetary gear train 1040 in the two-rowplanetary TV coupling mechanism 1200 are two-stage planetary geartrains, and the third planetary gear train 1050 in the single-rowplanetary differential coupling mechanism 1300 is a single-row planetarygear train. The structural simplified diagram is shown in the figure.

Embodiment 4

As shown in FIG. 4, in the present embodiment, the first planetary geartrain 1030 and the second planetary gear train 1040 in the two-rowplanetary TV coupling mechanism 1200 are two-stage planetary geartrains, and the third planetary gear train 1050 in the single-rowplanetary differential coupling mechanism 1300 is a two-stage planetarygear train. The structural simplified diagram is shown in the figure.

Solutions shown in FIGS. 1-4 are realizable embodiment structuresolutions of an electric differential with a torque vectoring functionin the present invention. However, in consideration of system inertialoss and running efficiency, an embodiment solution shown in FIG. 1 isan optimal solution, a less-preferred solution is the solution shown inFIG. 3, and then are the solutions shown in FIG. 2 and FIG. 4.

Operating principles of the electric differential with the torquevectoring function in the present invention are as follows:

The operating principles are described by taking the structuralsimplified diagram of the embodiment of the electric differential withthe torque vectoring function shown in FIG. 1 as an example.

When an automobile goes straight, wheels on the left and right sideshave the same drive torques, and torque vectoring is not needed.Therefore, the TV control motor 1001 has no control electrical signal;the TV control motor is not started; and the automobile is driven onlyby the main drive motor 1002. The torque outputted by the main drivemotor 1002 is increased by the main drive motor reducing mechanism 1500,and acts on the differential housing 1401. Due to an equal vectoringprinciple of the torque of the traditional bevel gear differentialmechanism 1400, the torque that acts on the differential housing 1401 isequally vectored to the first half shaft 1402 and the second half shaft1403 so as to drive the automobile to run. If the rotating direction ofthe wheel during drive of the automobile is set as a positive direction,an opposite direction is a negative direction. At this moment, thedifferential housing 1401, the first half shaft 1402 and the second halfshaft 1403 have the same rotation speed; and the planetary gears 1052 ofthe third planetary gear train 1050 only revolve with the differentialhousing 1401 and do not rotate. Therefore, the inner gear ring 1051 andthe sun gear 1054 rotate at equal speed. Because the sun gear 1034 ofthe first planetary gear train 1030 and the sun gear 1054 of the thirdplanetary gear train 1050 have the same rotation speed and the sun gear1044 of the second planetary gear train 1040 and the inner gear ring1051 of the third planetary gear train 1050 are formed into a whole, thesun gear 1034 in the first planetary gear train 1030 and the sun gear1044 in the second planetary gear train 1040 rotate at equal speed.Because the first planetary gear train 1030 and the second planetarygear train 1040 share one planet carrier and two sun gears also have thesame rotation speed, the inner gear ring 1031 and the inner gear ring1041 have the same rotation speed. The inner gear ring 1041 is fixed andhas a rotation speed of 0. Thus, the inner gear ring 1031 also has arotation speed of 0. The TV reducing mechanism 1100 only changes thetorque size outputted by the TV control motor 1001 and does not changethe positive direction and the negative direction of the outputtedtorque. Therefore, when the automobile goes straight, an inner rotor ofthe TV control motor 1001 also has a rotation speed of 0; the TV controlmotor is not started and does not output the torque; and the automobileis driven only by the main drive motor 1002. A torque vectoring flow isshown in FIG. 5.

When the automobile makes normal differential turning, wheels on theleft and right sides have the same drive torques, and torque vectoringis not needed. Therefore, the TV control motor 1001 has no controlelectrical signal; the TV control motor is not started; and theautomobile is driven only by the main drive motor 1002. The torqueoutputted by the main drive motor 1002 is increased by the main drivemotor reducing mechanism 1500, and acts on the differential housing1401. Due to an equal vectoring principle of the torque of thetraditional bevel gear differential mechanism 1400, the torque that actson the differential housing 1401 is equally vectored to the first halfshaft 1402 and the second half shaft 1403 so as to drive the automobileto run.

By taking normal differential left turning of the automobile as anexample, if the rotation direction of the wheel during drive of theautomobile is set as a positive direction, an opposite direction is anegative direction. For the third planetary gear train 1050, the formulaof the rotation speed of the single-row planetary gear train is:n _(S5) +k ₅ n _(S5)−(k ₅+1)n _(PC5)=0

In the formula, n_(S5) is the rotation speed of the sun gear 1054 of thethird planetary gear train 1050; n_(R5) is the rotation speed of theinner gear ring 1051 of the third planetary gear train; n_(PC5) is therotation speed of the planet carrier 1053 of the third planetary geartrain; and k₅ is a planetary row characteristic parameter of the thirdplanetary gear train. Because the automobile turns left, the rotationspeed of the differential housing 1401 is greater than the rotationspeed of the first half shaft 1402 and then:n _(S5) <n _(PC5)then:n _(S5) <n _(R5)

Namely, the rotation speed of the sun gear 1054 in the third planetarygear train 1050 is smaller than the rotation speed of the inner gearring 1051. Thus, in the two-row planetary TV coupling mechanism 1200,the rotation speed of the sun gear 1034 in the first planetary geartrain 1030 is smaller than the rotation speed of the sun gear 1044 inthe second planetary gear train 1040. Because the first planetary geartrain 1030 and the second planetary gear train 1040 share one planetcarrier, the two-row planetary TV coupling mechanism 1200 has:n _(S3) +kn _(R3) =n _(S4) +kn _(R4)

In the formula, n_(S3) is the rotation speed of the sun gear 1034 of thefirst planetary gear train 1030; n_(R3) is the rotation speed of theinner gear ring 1031 in the first planetary gear train 1030; n_(S4) isthe rotation speed of the sun gear 1044 of the second planetary geartrain 1040; n_(R4) is the rotation speed of the inner gear ring 1041 inthe second planetary gear train 1040; and k is a planetary rowcharacteristic parameter of the first planetary gear train 1030 and thesecond planetary gear train 1040. Because:n _(S3) <n _(S4) and n _(R4)=0,n _(R3)>0 is obtained.

Namely, the rotation speed of the inner gear ring 1031 in the firstplanetary gear train 1030 is positive, so the rotation speed of theinner rotor of the TV control motor 1001 is also positive. Therefore,when the automobile makes normal differential left turning, the TVcontrol motor 1001 does not input an electrical signal or output atorque; and the hollow shaft type inner rotor of the TV control motor isdragged by the torque vectoring device 2000 to rotate in the positivedirection. A torque vectoring flow is shown in FIG. 6.

Similarly, when the automobile makes normal differential right turning,the TV control motor 1001 does not input an electrical signal or outputa torque; and the hollow shaft type inner rotor of the TV control motoris dragged by the torque vectoring device 2000 to rotate in the negativedirection. A torque vectoring flow is also shown in FIG. 6.

When the automobile is turned at medium and high speed, a torque on awheel on an inner side should be vectored to a wheel on an outer side toincrease turning maneuverability. If the rotating direction of the wheelduring drive of the automobile is set as a positive direction, anopposite direction is a negative direction; and left turning of theautomobile is taken as an example for making analysis. At this moment, amotor controller controls the TV control motor 1001 to output a positivetorque T₀ (T₀ is a positive value); after the torque is increased byreducing speed by the TV reducing mechanism 1100, a moment inputted intothe inner gear ring 1031 in the two-row planetary TV coupling mechanism1200 is iT₀, wherein i is a transmission ratio of the TV reducingmechanism 1100. Thus, a moment inputted into the first half shaft 1402by the sun gear 1034 in the first planetary gear train 1030 is

$- {\frac{{iT}_{0}}{k}.}$Then, a moment inputted into the inner gear ring 1051 of the single-rowplanetary differential coupling mechanism 1300 by the TV control motor1001 is

$\frac{{iT}_{0}}{k}.$Therefore, the torque inputted into the first half shaft 1402 of the sungear 1054 in the third planetary gear train 1050 is

${- \frac{{iT}_{0}}{{kk}_{5}}},$and a moment inputted into the differential housing 1401 by the planetcarrier 1053 is

$\frac{{i\left( {k_{5} + 1} \right)}T_{0}}{{kk}_{5}}.$A moment which is equally vectored to the first half shaft 1402 and thesecond half shaft 1403 by the differential housing 1401 is

$\frac{{i\left( {k_{5} + 1} \right)}T_{0}}{2\;{kk}_{5}}.$Therefore, the moment inputted into the first half shaft 1402 by the TVcontrol motor 1001 is finally formed by a sum of three parts, i.e., themoment inputted into the first half shaft 1402 by the sun gear 1034 inthe first planetary gear train 1030, the moment inputted into the firsthalf shaft 1402 by the sun gear 1054 in the third planetary gear train1050, and the moment equally vectored to the first half shaft 1402 bythe differential housing 1401. The result of the moment is

$\frac{{i\left( {k_{5} + 1} \right)}T_{0}}{2\;{kk}_{5}}.$The moment finally inputted into the second half shaft 1403 by the TVcontrol motor 1001 is

$\frac{{i\left( {k_{5} + 1} \right)}T_{0}}{2\;{kk}_{5}}.$It can be seen from the above that, the moment inputted into the firsthalf shaft 1402 and the second half shaft 1403 by the TV control motor1001 is equal and opposite in directions. Therefore, the totallongitudinal drive torque is not changed; the torque of the wheel on theleft side connected with the first half shaft 1402 is decreased; thetorque of the wheel on the right side connected with the second halfshaft 1403 is increased; a yawing moment contributing to left turningmay be generated; the left-turning maneuverability of the automobile isincreased. It should be indicated that, the rotation speed of the TVcontrol motor 1001 at this moment is equal to the rotation speed whenthe automobile makes normal differential left turning. The torquevectoring flow is shown in FIG. 7. It should be indicated that, if theTV control motor outputs a negative torque at this moment, then thedrive torque will be vectored from the wheel on the right side to thewheel on the left side, and a yawing moment that prevents over-steeringof the vehicle is generated for maintaining automotive stability.

Similarly, when the automobile turns right at medium and high speed, themotor controller controls the TV control motor 1001 to output a negativetorque, and a yawing moment contributing to right turning may begenerated on premise of not changing the total longitudinal drivetorque, thereby enhancing the right-turning maneuverability of theautomobile. It should be indicated that, the rotation speed of the TVcontrol motor 1001 at this moment is equal to the rotation speed whenthe automobile makes normal differential right turning. The torquevectoring flow is shown in FIG. 8. It should be indicated that, if theTV control motor outputs a positive torque at this moment, then thedrive torque will be vectored from the wheel on the left side to thewheel on the right side, and a yawing moment that prevents over-steeringof the vehicle is generated for maintaining the automotive stability.

Although the embodiments of the present invention are disclosed above,the present invention is not only limited to applications listed indescription and embodiments and is completely applicable to variousfields suitable for the present invention. Additional modifications maybe easily realized by those skilled in the art. Therefore, the presentinvention is not limited to specific details and illustrated anddescribed figures herein on premise of not deviating from generalconcepts defined by claims and equivalent scopes.

We claim:
 1. An electric differential with a torque vectoring function,comprising: a main drive mechanism arranged on one side of adifferential, wherein an output end of the main drive mechanism isconnected with a differential housing for transferring rotating power tothe differential housing to drive a vehicle to run; a TV control drivemechanism arranged on the other side of the differential for outputtingtorque vectoring control power; a first single-row planetary gear trainincluding a first sun gear, a first planetary gear, a first planetcarrier and a first gear ring, wherein the first sun gear is coaxiallyand fixedly connected with a first half shaft, and the first gear ringis connected with an output end of the TV control drive mechanism; asecond single-row planetary gear train including a second sun gear, asecond planetary gear, a second planet carrier and a second gear ring,wherein the second gear ring is fixed to a drive axle housing, thesecond planet carrier is fixedly connected with the first planetcarrier, and the second sun gear is rotatably supported on the firsthalf shaft; and a third single-row planetary gear train including athird sun gear, a third planetary gear, a third planet carrier and athird gear ring, wherein the third sun gear is coaxially and fixedlyconnected with the first half shaft, the third gear ring is fixedlyconnected with the second sun gear, and the third planet carrier isfixedly connected with the differential housing, wherein the secondsingle-row planetary gear train and the first single-row planetary geartrain have a same diameter.
 2. The electric differential with a torquevectoring function according to claim 1, wherein the TV control drivemechanism comprises a TV control motor and a TV reducing mechanism. 3.The electric differential with a torque vectoring function according toclaim 2, wherein the TV control motor comprises a hollow output shaft;and the first half shaft is rotatably supported on the hollow outputshaft and penetrates out of the hollow output shaft.
 4. The electricdifferential with a torque vectoring function according to claim 2,wherein TV reducing mechanism comprises: a fourth single-row planetarygear train including a fourth sun gear, a fourth planetary gear, afourth planet carrier and a fourth gear ring, wherein the fourth sungear is fixedly connected with the hollow output shaft, and the fourthgear ring is fixed to the drive axle housing; and a fifth single-rowplanetary gear train including a fifth sun gear, a fifth planetary gear,a fifth planet carrier and a fifth gear ring, wherein the fifth sun gearis fixedly connected with the fourth planet carrier, the fifth gear ringis fixed to the drive axle housing, and the fifth planet carrier is acontrol output end that is connected with the first gear ring.
 5. Theelectric differential with a torque vectoring function according toclaim 1, wherein the main drive mechanism comprises a main drive motorand a main reducing mechanism.
 6. The electric differential with atorque vectoring function according to claim 5, wherein the main drivemotor comprises a hollow output shaft; and a second half shaft isrotatably supported on the hollow output shaft and penetrates out of thehollow output shaft.
 7. The electric differential with a torquevectoring function according to claim 5, wherein the main reducingmechanism comprises: a seventh single-row planetary gear train includinga seventh sun gear, a seventh planetary gear, a seventh planet carrierand a seventh gear ring, wherein the seventh sun gear is fixedlyconnected with an output shaft of the main drive motor, and the seventhgear ring is fixed to the drive axle housing; and a sixth single-rowplanetary gear train including a sixth sun gear, a sixth planetary gear,a sixth planet carrier and a sixth gear ring, wherein the sixth sun gearis fixedly connected with the seventh planet carrier, the sixth gearring is fixed to the drive axle housing, and the sixth planet carrier isfixedly connected with the differential housing.
 8. An electricdifferential with a torque vectoring function, comprising: a main drivemechanism arranged on one side of a differential, wherein an output endof the main drive mechanism is connected with a differential housing fortransferring rotating power to the differential housing to drive avehicle to run; a TV control drive mechanism arranged on the other sideof the differential for outputting torque vectoring control power; afirst single-row two-stage planetary gear train including a first sungear, a first two-stage planetary gear, a first planet carrier and afirst gear ring, wherein the first sun gear is coaxially and fixedlyconnected with a first half shaft, and the first gear ring is connectedwith an output end of the TV control drive mechanism; a secondsingle-row two-stage planetary gear train including a second sun gear, asecond two-stage planetary gear, a second planet carrier and a secondgear ring, wherein the second gear ring is fixed to a drive axlehousing, the second planet carrier is fixedly connected with the firstplanet carrier, and the second sun gear is rotatably supported on thefirst half shaft; and a third single-row planetary gear train includinga third sun gear, a third planetary gear, a third planet carrier and athird gear ring, wherein the third sun gear is coaxially and fixedlyconnected with the first half shaft, the third gear ring is fixedlyconnected with the second sun gear, and the third planet carrier isfixedly connected with the differential housing, wherein the secondsingle-row two-stage planetary gear train and the first single-rowtwo-stage planetary gear train have a same diameter.
 9. An electricdifferential with a torque vectoring function, comprising: a main drivemechanism arranged on one side of a differential, wherein an output endof the main drive mechanism is connected with a differential housing fortransferring rotating power to the differential housing to drive avehicle to run; a TV control drive mechanism arranged on the other sideof the differential for outputting torque vectoring control power; afirst single-row planetary gear train including a first sun gear, afirst planetary gear, a first planet carrier and a first gear ring,wherein the first sun gear is coaxially and fixedly connected with afirst half shaft, and the first gear ring is connected with an outputend of the TV control drive mechanism; a second single-row planetarygear train including a second sun gear, a second planetary gear, asecond planet carrier and a second gear ring, wherein the second gearring is fixed to a drive axle housing, the second planet carrier isfixedly connected with the first planet carrier, and the second sun gearis rotatably supported on the first half shaft; and a third single-rowtwo-stage planetary gear train including a third sun gear, a thirdtwo-stage planetary gear, a third planet carrier and a third gear ring,wherein the third sun gear is coaxially and fixedly connected with thefirst half shaft, the third gear ring is fixedly connected with thesecond sun gear, and the third planet carrier is fixedly connected withthe differential housing, wherein the second single-row planetary geartrain and the first single-row planetary gear train have a samediameter.